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Date:   Mon, 25 Oct 2021 09:34:10 +0200
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Subject: Re: [RFC 03/16] KVM: selftests: handle encryption bits in page tables
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To:     Michael Roth <michael.roth@amd.com>
Cc:     linux-kselftest@vger.kernel.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        Nathan Tempelman <natet@google.com>,
        Marc Orr <marcorr@google.com>,
        Steve Rutherford <srutherford@google.com>,
        Sean Christopherson <seanjc@google.com>,
        Mingwei Zhang <mizhang@google.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Varad Gautam <varad.gautam@suse.com>,
        Shuah Khan <shuah@kernel.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Ricardo Koller <ricarkol@google.com>,
        Jim Mattson <jmattson@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>
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 <31db4c63-218a-5b26-f6ed-d30113f95e29@redhat.com>
 <20211024164945.mt62qjrld3dwssv4@amd.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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On 24/10/21 18:49, Michael Roth wrote:
> So test code would need to consider cases where addr_gpa2raw() needs to be
> used to set the C-bit (which is basically only when they want to mix usage
> of the vm_phy_page[s]_alloc with their own mapping of the guest page tables,
> which doesn't seem to be done in any existing tests anyway).

Yes, and it seems like a more rare case in general.

> The library code would need these addr_gpa2raw() hooks in places where
> it calls virt_*map() internally. Probably just a handful of places
> though.

Either that, or you can have virt_*map that consults the encryption 
bitmap, and virt_*map_enc (or _raw, doesn't matter) that takes the 
encryption state explicitly as a bool.

> Even in this alternative approach though, having addr_gpa2hva() silently
> mask away C-bit still seems useful for the reasons above, but again, no
> strong feelings one way or the other on that.

Ok, keep it the way you find more useful.

Paolo